Disclaimer: I’m not sure these will make for a better calibration if you mostly want to test low CRI lights with lux meters, but the smooth spectrum of the Optisolis would be a great reference for future.
Just like with the S2+ and BLF348 or any other light, price for measurement is 15 euros per light plus intl shipping (4.70 or 7.50 euros depending on weight). Does not include the price of the light itself.
From Lisun:
The IS-0.5M (19.685 inch) is suitable for LEDs, LED modules, High Power LED, mini bulbs and other small lamps. The flux testing range is 0.001 to 1,999 lumen.
I believe Maukka uses a neutral density filter over the sensor to allow for much higher outputs than the rated 2,000 lumen. These filters seem to give a very consistent reduction in lumens.
Surely there must be a lumen limit, but who knows what it is.
So for high power stuff you would just test the light on a low mode and then calculate the max based on some curve related to the expected diminished returns?
Relative brightness using two measurements outside the sphere I would guess or just heavily filter the sensor and take the same 2 readings to re-calibrate
I suspect something like measuring Low in the sphere. Let’s say it’s 953 lumen. Then do a ceiling bounce. Let’s say it measures 110 lux. That’s 8.66 lumen per lux. Then do the exact same ceiling bounce, except on Turbo. If we get 769 lux, then we can calculate the increase which comes to 6,662 lumen.
This makes sense in theory, but I’m not sure about in reality.
I did the same thing since I hat to measure a Olight X9R.
This flahlight has a sensor which lowers the output if something is too near to the reflector. With this I could not check the higher output-levels with my box. I checked lux in our toilette to calculate the lumen of the higher levels.
After that I made the same with my Imalent DX80, I found out that my box shows too low values on the higher output levels above 10,000 lumen.
Than I build a sphere and rechecked it with the Imalent MS12 and R90C. And there are some differences in higher levels too. Around 15,000 (R90C) or 20000 (MS12) there were some differences.
For the DX80 I rececked my lumen readings with the readings from spheres of other TLF/BLF members.